Search

This study focused on evaluating the rutting performance of three different highly polymer-modified asphalt (HiMA) binders (i.e., O, T and B) using binder-based [i.e., multiple stress creep recovery (MSCR) and force ductility (FD)] and mix-based [flow number (FN) and Hamburg wheel tracking test (HWTT)] rutting performance tests. The binder-based rutting indicators were compared with mix rutting performance to determine a parameter that can help in the correct prediction of HiMA rutting resistance. In addition, the study looked into application of a simple performance test, the indirect rutting tolerance index (IDEAL-RT), for HiMA mix rutting prediction. The MSCR test revealed different rankings of recovery at 0.1- and 3.2-kPa stress levels. Moreover, the T and B binders did not satisfy the stress sensitivity criteria (Jnr_difference) of Max 75%. The force ductility tests revealed that the peak force observed for polymer network phase in HiMA was significantly higher than base binder stiffness, which is in contrast with force distribution in polymer-modified binders (PMBs). The mix rutting resistance ranking (O>T>B) was similar in all the tests (i.e., FN, HWTT, and IDEAL-RT). Although IDEAL-RT can be used to compare the rutting resistances of HiMA mixes, detailed future work is required to establish its acceptability in comparing various types of mixes and the minimum requirements of RTIndex. The comparison between binder and mix rutting indicators demonstrated that MSCR testing on binder at stress levels of 6.4 kPa and higher can be used to predict the rutting resistance of HiMA binders. Parameters like slope and cohesion energy and a newly introduced parameter—work done for polymer activation (WPA)—from FD tests can be used to determine the polymeric phase dominance in HiMA binders. Overall, this study provides pavement stakeholders with a framework for rightly predicting the rutting resistance and polymeric phase dominance of HiMA binders and mixes using MSCR, FD, and IDEAL-RT tests. [ABSTRACT FROM AUTHOR]

• CNT addition improve the rutting performance of asphalt binder. • CNT addition may increase the stress sensitivity of asphalt binder. • It is desirable to have a higher value of η m for improved rutting performance. • Modified power law can model nonlinear strain response in the recovery period. • CNT addition also improve the performance of asphalt binder under sustained loading. The present study aimed at evaluating the rutting performance of Carbon Nano Tube (CNT) modified asphalt binder under different loading conditions. CNT content was varied as 0%, 0.4%, 0.75%, 1.5% and 2.25% by the weight of control binder. Superpave rutting parameter (G*/Sinδ) and Shenoy parameter (G*/(1-(1/TanδSinδ))) were initially evaluated using temperature sweep test. Though both parameters showed a similar trend, the later one found to have more sensitivity towards evaluating unrecoverable strain value. Creep-recovery test was further conducted at four different stress levels (100 Pa, 3200 Pa, 5000 Pa, and 10000 Pa) to understand the effect of CNT under cyclic loading-unloading condition. Improvement in recovery value and a corresponding decrease in non-recoverable creep compliance value was observed with the addition of CNT. Further attempt was made to model the strain response from creep-recovery test using the Burgers model and Power model. Based upon the variation of viscous component of steady flow obtained from the Burgers model, CNT addition found to improve the rutting performance. Further, the power model also showed an excellent prediction of strain response under creep period, however, deviation from the experimentally observed response was observed in the recovery period. Modification to the power law model was done which significantly improved the strain prediction in the recovery period. Likewise, the effects of CNT under sustained loading condition was evaluated using a creep test at two different stress levels (100 Pa and 3200 Pa). Incremental dosages of CNT shifted the binder response from linear to nonlinear viscoelastic region at comparatively lower creep period. Significant decrease in deformation rate was also observed with CNT addition. [ABSTRACT FROM AUTHOR]

Modification of asphalt binder with Elvaloy (Elv) and polyphosphoric acid (PPA) has been reported to have better performance. However, such modification may increase mixing and compaction temperatures of asphalt binder. Furthermore, the positive effect of PPA may get neutralized with the addition of lime, which can lead to inferior performance of asphalt binders. Recently, different types of warm mix additives (WMA) are being introduced to reduce production and construction temperatures of asphalt binder. However, the effects of WMA additives with and without lime on various rheological response of PPA + Elv modified asphalt binder is not well understood so far. Therefore, the present study was undertaken to evaluate the rutting and fatigue performance of PPA + Elv modified asphalt binder (referred as Control binder) containing threeWMAadditives (water, chemical, and wax-based) with and without lime. The multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS) tests were conducted to capture the rutting and fatigue performance of asphalt binders, respectively. The results show that rutting and fatigue performance of Control asphalt binder decreased with the addition of chemical and water-based WMA additives. The performance of Control asphalt binder further deteriorated when these WMA additives (chemical and water) were used with lime. Interestingly, the addition of wax showed higher rutting resistance and similar fatigue life as that of Control asphalt binder. The addition of lime with wax additive showed improved rutting resistance and reduced fatigue life compared with Control asphalt binder. Regardless of the type of WMA additives, the addition of lime decreased the fatigue life of Control asphalt binder. The adverse effect of lime was prominent when used with wax compared with water and chemical-based WMA additives. Furthermore, the addition of WMA additives increased the stress sensitivity of Control asphalt binder. The stress sensitivity of asphalt binder further increased when wax and chemical-based WMA additives were used with lime. However, use of water-based WMA additive and lime reduced the stress sensitivity of Control asphalt binder. Overall, it can be concluded that the performance of Elv + PPA modified asphalt binder depends largely on the type of WMA additives and their combination with lime. [ABSTRACT FROM AUTHOR]

Recent impetus on utilization of different types of nanomaterials for modification of asphalt binders has motivated the authors to undertake the present study. The present study evaluated the rutting, fatigue and moisture damage performance of nanoclay (CL-30B) modified asphalt binder based on newly adopted test methods. Based on Superpave rutting parameter, it was observed that rutting resistivity of a binder increases with an increase in CL-30B content. Moisture resistivity of CL-30B modified asphalt binder with different types of aggregates system was studied using Surface Free Energy (SFE) approach. The SFE components of nanoclay modified binder were measured using Wilhelmy plate method. Four different types of aggregates (Basalt, Limestone, Sandstone and Granite) were chosen for the study. Overall increase in total SFE of the binder was observed with addition of CL-30B. Increase in work of cohesion and decrease in work of debonding was observed with an increase in CL-30B for all type of considered aggregate. Based on Energy ratio (ER), asphalt binder with basaltic aggregate was found to have better moisture damage resistivity among different types of aggregate selected in this study. The fatigue performance of CL-30B modified binder was evaluated using Linear Amplitude Sweep (LAS) test which is based on Visco Elastic Continuum Damage (VECD) theory. The analyses of the data showed that addition of CL-30B enhances fatigue life of a binder. The study showed potential of CL-30B to enhance various rheological performance of a binder for better and long lasting pavements. [ABSTRACT FROM AUTHOR]

The present study aims to evaluate rutting, fatigue, and rheological performances of a SBS co-polymer modified binder (PMB40) blended with different percentages (i.e., 0%, 15%, 25% and 40%) of reclaimed asphalt pavement (RAP) binder. The change in viscosity, mixing and compaction temperatures, and temperature susceptibility of PMB40 binder mixed with RAP were measured using Brookfield viscometer. Furthermore, linear viscoelastic range (LVE) and time-temperature sweep tests were conducted to characterize binders. The rutting and fatigue performance of PMB40 binder with varying percentages of RAP was evaluated using multi stress creep and recovery (MSCR) and linear amplitude sweep (LAS) tests, respectively. The change in chemical composition of PMB40 binder with addition of RAP was determined by Fourier transform infrared (FTIR) spectroscopy. The results showed that addition of RAP makes PMB40 binder stiff and less temperature susceptible, however, it did not change mixing and compaction temperatures significantly. Furthermore, high temperature performance grade (PG) of PMB40 binder was unaltered with addition of RAP, which is contrary to findings reported in literature. The MSCR test showed significant reduction in recovery and increment in non-recoverable creep compliance of PMB40 binder with addition of RAP, indicating a poor rutting resistance of the binder with inclusion of RAP. The LAS test showed that rate of damage increases and number of cycles to fatigue failure of PMB40 binder decreases with addition of RAP. The FTIR test confirmed increase in sulfoxide and carbonyl content with addition of RAP. A good correlation was found for ICO and ISBS indices obtained from FTIR with rheological properties of PMB40 binder. It is to be noted that the findings presented in this paper are based on one modified binder and one RAP source, thus it is recommended that effects of different RAP sources on performance of SBS modified binder be studied in detail. Further, effects of ageing (short term and long term) should be studied to have insight into characterization of RAP blended binders. It is also recommended that binder's rheological performance tests be validated by conducting laboratory tests on asphalt mixes. [ABSTRACT FROM AUTHOR]

• Effect of bio-oil on rheological performance of base binder and field aged RAP binder is investigated. • Use of higher percentage of bio-oil may make binder susceptible to high-temperature aging and improve the fatigue performance of base binder. • To explore bio-oil as a potential rejuvenator, softening point, kinematic viscosity, high-temperature PG and MSCR tests were conducted. • Bio-oil can be used as softening agent for aged binders. The present study evaluates the effects of using bio-oil derived from waste wood biomass on physical properties, aging, fatigue and rutting performance of base binder. A base binder (Viscosity Grade VG30) was blended with 2%, 4%, 6%, 8% and 10% of bio-oil by total weight of the binder. Along with physical properties tests (penetration, softening point and viscosity), rutting and fatigue performance of the bio-oil modified binder was evaluated using multiple stress creep recovery (MSCR), and linear amplitude sweep (LAS), tests, respectively. Furthermore, the aging index was determined to observe the oxidation characteristics of bio-oil modified asphalt binder. The results showed that the blending of bio-oil increased the penetration and decreased the softening point and viscosity of the base binder. Based on Indian Standard 73:2013 specification, it was observed that blending of 2% and 4% bio-oil satisfies VG20 and VG10 binder properties, respectively. Increased percent of bio-oil modified binder showed high aging susceptibility. Addition of bio-oil decreased rutting performance, while it improved the fatigue and thermal cracking resistance. Bio-oil as a rejuvenator was explored by blending it with RAP binder. It was found that addition of bio-oil reduces viscosity and high PG of recycled asphalt pavement (RAP) binder, thus showed the potentiality to use as softener for aged binder. [ABSTRACT FROM AUTHOR]